The invention relates to a manual hydraulic apparatus with a traction/pressure installation, for example, a hole punch apparatus, with a hydraulic piston which can e moved with respect to a cylindrical housing, and with a holding-up part and a fastening installation, for example, for a piercing punch.
Different variants of such manual hydraulic apparatuses are already known. One such manual apparatus cannot only be used as a transportable perforation apparatus, for example, for the punching of holes in metal sheets, it can also, in another variant, be used as a blind riveting apparatus. With regard to the latter possibility, reference is made, for example, to the state of the prior art according to EP B1 62 206.
In the known manual hydraulic apparatuses, the design of the traction/pressure installation is not yet considered to be satisfactory.
The hydraulic piston of the known manual hydraulic apparatus retracts, when pressure is applied, pulling the piercing punch to the apparatus, while the holding-up part remains fixed. Accordingly, the admission of the hydraulic piston must be from the front. Because, in addition, the hydraulic piston is still connected to the fastening installation, only a ring surface of the piston is available for the admission pressure. This surface must have the appropriate area, or a correspondingly high hydraulic pressure must be applied.